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/*! \file
  \brief Functor performing linear combination operations on planar-complex
  arrays
*/

#pragma once

#include "cutlass/cutlass.h"
#include "cutlass/numeric_types.h"
#include "cutlass/complex.h"
#include "cutlass/array_planar_complex.h"
#include "cutlass/functional.h"
#include "cutlass/numeric_conversion.h"

/////////////////////////////////////////////////////////////////////////////////////////////////

namespace cutlass {
namespace epilogue {
namespace thread {

/////////////////////////////////////////////////////////////////////////////////////////////////

/// Applies a linear combination operator to arrays of planar-complex elements.
///
/// D = alpha * accumulator + beta * source + uniform
///
/// Note, as with most CUTLASS components for planar complex, the template
/// arguments describe the underlying real data type.
template <typename ElementOutput_,  ///< Data type used to load and store
                                    ///< tensors
          int Count,  ///< Number of elements computed per operation
          typename ElementAccumulator_ =
                  ElementOutput_,  ///< Accumulator data type
          typename ElementCompute_ =
                  ElementOutput_,  ///< Data type used to compute linear
                                   ///< combination
          FloatRoundStyle Round = FloatRoundStyle::round_to_nearest>
class LinearCombinationPlanarComplex {
public:
    using ElementOutput = ElementOutput_;
    using ElementAccumulator = ElementAccumulator_;
    using ElementCompute = ElementCompute_;

    static int const kCount = Count;

    using FragmentOutput = ArrayPlanarComplex<ElementOutput, kCount>;
    using FragmentAccumulator = ArrayPlanarComplex<ElementAccumulator, kCount>;
    using ComputeFragment = ArrayPlanarComplex<ElementCompute, kCount>;

    static FloatRoundStyle const kRound = Round;

    /// Host-constructable parameters structure
    struct Params {
        complex<ElementCompute> alpha;  ///< scales accumulators
        complex<ElementCompute> beta;   ///< scales source tensor
        complex<ElementCompute> const*
                alpha_ptr;  ///< pointer to accumulator scalar - if not null,
                            ///< loads it from memory
        complex<ElementCompute> const*
                beta_ptr;  ///< pointer to source scalar - if not null, loads it
                           ///< from memory

        //
        // Methods
        //

        CUTLASS_HOST_DEVICE
        Params()
                : alpha(ElementCompute(1)),
                  beta(ElementCompute(0)),
                  alpha_ptr(nullptr),
                  beta_ptr(nullptr) {}

        CUTLASS_HOST_DEVICE
        Params(complex<ElementCompute> alpha, complex<ElementCompute> beta)
                : alpha(alpha),
                  beta(beta),
                  alpha_ptr(nullptr),
                  beta_ptr(nullptr) {}

        CUTLASS_HOST_DEVICE
        Params(complex<ElementCompute> const* alpha_ptr,
               complex<ElementCompute> const* beta_ptr)
                : alpha(complex<ElementCompute>()),
                  beta(complex<ElementCompute>()),
                  alpha_ptr(alpha_ptr),
                  beta_ptr(beta_ptr) {}
    };

private:
    //
    // Data members
    //

    complex<ElementCompute> alpha_;
    complex<ElementCompute> beta_;

public:
    /// Constructs the function object, possibly loading from pointers in host
    /// memory
    CUTLASS_HOST_DEVICE
    LinearCombinationPlanarComplex(Params const& params) {
        alpha_ = (params.alpha_ptr ? *params.alpha_ptr : params.alpha);
        beta_ = (params.beta_ptr ? *params.beta_ptr : params.beta);
    }

    /// Returns true if source is needed
    CUTLASS_HOST_DEVICE
    bool is_source_needed() const {
        return beta_.real() != ElementCompute(0) ||
               beta_.imag() != ElementCompute(0);
    }

    /// Functionally required for serial reduction in the epilogue
    CUTLASS_HOST_DEVICE
    void set_k_partition(int k_partition, int k_partition_count) {
        if (k_partition) {
            beta_ = ElementCompute(1);
        }
    }

    /// Computes linear scaling: D = alpha * accumulator + beta * source
    CUTLASS_HOST_DEVICE
    FragmentOutput operator()(FragmentAccumulator const& accumulator,
                              FragmentOutput const& source) const {
        // Convert source to interal compute numeric type
        NumericArrayConverter<ElementCompute, ElementOutput, kCount, Round>
                source_converter;
        NumericArrayConverter<ElementCompute, ElementAccumulator, kCount, Round>
                accumulator_converter;

        ComputeFragment converted_source(source_converter(source.real),
                                         source_converter(source.imag));

        ComputeFragment converted_accumulator(
                accumulator_converter(accumulator.real),
                accumulator_converter(accumulator.imag));

        // Perform binary operations
        ComputeFragment intermediate;

        multiplies<Array<ElementCompute, kCount> > mul_op;
        multiply_add<Array<ElementCompute, kCount> > mul_add_op;

        // complex multiply: I = beta * C
        intermediate.real = mul_op(beta_.real(), converted_source.real);
        intermediate.imag = mul_op(beta_.real(), converted_source.imag);

        intermediate.real = mul_add_op(-beta_.imag(), converted_source.imag,
                                       intermediate.real);
        intermediate.imag = mul_add_op(beta_.imag(), converted_source.real,
                                       intermediate.imag);

        // complex multiply-add: I = alpha * AB + I
        intermediate.real = mul_add_op(
                alpha_.real(), converted_accumulator.real, intermediate.real);
        intermediate.imag = mul_add_op(
                alpha_.real(), converted_accumulator.imag, intermediate.imag);

        intermediate.real = mul_add_op(
                -alpha_.imag(), converted_accumulator.imag, intermediate.real);
        intermediate.imag = mul_add_op(
                alpha_.imag(), converted_accumulator.real, intermediate.imag);

        // Convert to destination numeric type
        NumericArrayConverter<ElementOutput, ElementCompute, kCount, Round>
                destination_converter;

        return FragmentOutput(destination_converter(intermediate.real),
                              destination_converter(intermediate.imag));
    }

    /// Computes linear scaling: D = alpha * accumulator + beta * source
    CUTLASS_HOST_DEVICE
    FragmentOutput operator()(FragmentAccumulator const& accumulator) const {
        // Convert source to interal compute numeric type
        NumericArrayConverter<ElementCompute, ElementAccumulator, kCount, Round>
                accumulator_converter;

        ComputeFragment converted_accumulator(
                accumulator_converter(accumulator.real),
                accumulator_converter(accumulator.imag));

        // Perform binary operations
        ComputeFragment intermediate;

        multiplies<Array<ElementCompute, kCount> > mul_op;
        multiply_add<Array<ElementCompute, kCount> > mul_add_op;

        // complex multiply-add: I = alpha * AB + I
        intermediate.real =
                mul_add_op(alpha_.real(), converted_accumulator.real);
        intermediate.imag =
                mul_add_op(alpha_.real(), converted_accumulator.imag);

        intermediate.real = mul_add_op(
                -alpha_.imag(), converted_accumulator.imag, intermediate.real);
        intermediate.imag = mul_add_op(
                alpha_.imag(), converted_accumulator.real, intermediate.imag);

        // Convert to destination numeric type
        NumericArrayConverter<ElementOutput, ElementCompute, kCount, Round>
                destination_converter;

        return FragmentOutput(destination_converter(intermediate.real),
                              destination_converter(intermediate.imag));
    }
};

/////////////////////////////////////////////////////////////////////////////////////////////////

}  // namespace thread
}  // namespace epilogue
}  // namespace cutlass

/////////////////////////////////////////////////////////////////////////////////////////////////
